The present invention relates to a method and a device for drilling in rock or in earth layers with impregnated diamond drill bits, i.e. drill bits with diamonds in the bit body.
In prior art drilling devices, e.g. for exploration drilling, of the kind which the present invention intends to improve one has the problem of obtaining good drill penetration and good service life at the same time. If the feed force is too low the drill bit is polished so that it very soon loses its cutting ability. If the feed force is too high the drill bit is quickly destroyed because of overheating. The problem of the operator is to continously watch the drilling parameters and correct if the drill penetration decreases. If the drill bit starts being blunt the cutting ability can be restored through momentary increase of the feed force and/or through momentary drastic decrease of the amount of flushing fluid. Since the ability of the operator to observe decreased drill penetration is limited restoration of the cutting abillity results in a large wear of the drill bit. Furthermore the manual sharpening of the drill bit results in a great risk that the drill bit is overheated and quickly destroyed.